Since we need to store the passwords during the migration, we are excited that Google now offers something they call Application-specific passwords. This works just like a regular password, but you can create multiple passwords and easily manage the access. This is great both for us and for our users. The password you provide us is less 'valuable' for an attacker and you can revoke the access to the password at any time.
Hence, our advice would be that your use 'Application-specific passwords' for you next YippieMove migration.